1. Field of the Invention
The invention relates to man-machine interface devices and in particular to manually operated control handles.
2. Description of Prior Art
Control handles, or joysticks, are used as man-machine interface elements generating output signals in response to hand, or thumb, applied movement or force. In general, joysticks divide into two main categories: (1) position joysticks, and (2) force joysticks. The difference between the two categories is the stiffness of the handle as perceived by the operator. In the force-type joysticks, the stiffness is very high and the perceived motion is virtually zero. In position joysticks, the perceived stiffness and motion range are dependent on the particular design.
The general construction of a joystick includes a housing that is usually mounted on a panel, a handle and a position, or force, sensing mechanism. In prior art position joysticks have usually been constructed with the handle suspended in two axes by a gimbel-type mechanism, wherein each rotation axis is provided with an angular pick-off such as a potentiometer. Force-type joysticks are simpler in construction, since the handle is fixedly attached to the housing. The force-sensing mechanism is comprised of strain sensors attached to the handle and is sensitive to deflection-induced strains in two axes.
Typical joysticks are described, for example, in U.S. Pat. Nos. 4,275,611, 4,250,378, 4,156,130 and 4,107,642. A typical force-type joystick is described in U.S. Pat. No. 3,832,895.
The disadvantages of prior art position joysticks are the complicated and bulky mechanical constructions needed to support the handle and angular pick-offs in two axes. In addition, no pick-off was employed that is suitable to both force and displacement-type joystick.